Sb5

Sb5 is a designation used in inorganic and cluster chemistry to denote a five-atom cluster composed of antimony (Sb). It is not a single, fixed molecule but a class of species that can exist as neutral Sb5 molecules or as charged clusters such as Sb5− or Sb5n+ depending on redox state and ligands. In many reports, Sb5 units appear as fragments within larger coordination compounds or as discrete ions stabilized by bulky counterions or donor solvents.

Structural motifs of Sb5 vary, with common features including Sb–Sb bonding and multicenter bonding characteristic of pnictogen clusters. The geometry can be influenced by charge, with neutral Sb5 sometimes adopting a near-planar or slightly folded arrangement, while charged forms may assume three-dimensional structures with distinct Sb–Sb distances. Bonding in heavier pnictogen clusters often involves three-center two-electron interactions.

Synthesis generally involves reduction or reductive coupling of antimony sources, such as antimony halides, in the presence of stabilizing ligands or templating cations. Gas-phase generation by laser ablation has also produced Sb5-containing clusters, detected by mass spectrometry and spectroscopy.

Occurrence and applications: Sb5 is not known as a naturally occurring mineral; it arises in laboratory-synthesized clusters or as transient fragments in broader antimony chemistry. Applications are primarily in fundamental cluster science, materials chemistry, and as a model for understanding bonding in heavier pnictogens. Research explores potential roles in catalysis or as building blocks for antimony-rich nanomaterials.

Related species include smaller Sb clusters such as Sb4 and larger polyantimony clusters such as Sb7 or Sb9, with contextual analogs in arsenic- and bismuth-containing chemistry.